Rolling stock connection systems are key to running longer and heavier trains as they provide both the connections of vehicles and the damping,providing the longitudinal suspension of the train.This paper focuses on t...Rolling stock connection systems are key to running longer and heavier trains as they provide both the connections of vehicles and the damping,providing the longitudinal suspension of the train.This paper focuses on the evolution of both connection and stiffness damping systems.Focus is on freight rolling stock,but passenger draw gears are also examined.It was found that connection systems have evolved from the buff and chain system used in the pioneer railways of the 1800s to the modern auto-coupler connection systems that are in-service worldwide today.Refined versions of the buff and chain coupling are,however,still in use in the EU,UK,South America and India.A wide range of auto-coupler systems are currently utilised,but the AAR coupler(Janney coupler)remains the most popular.A further variation that persists is the SA3 coupler(improved Wilson coupler)which is an alternative auto-coupler design used mainly throughout the former Soviet Union.Restricting the review to auto-coupler systems allowed the paper to focus on draft gears which revealed polymer,polymer-friction,steel spring-friction,hydraulic draft gears and sliding sill cushioning systems.Along with the single compressive draft gear units balanced and floating plate configurations are also presented.Typical draft gear acceptance standards are presented along with modelling that was included to aid in presentation of the functional characteristics of draft gears.展开更多
Inadequate management of large in-train forces transferred through coupler systems of a railway train leads to running and structural failures of vehicles.Understanding these phenomena and their mitigation requires ac...Inadequate management of large in-train forces transferred through coupler systems of a railway train leads to running and structural failures of vehicles.Understanding these phenomena and their mitigation requires accurate estimation of relative motions and in-train forces between vehicle bodies.Previous numerical studies have ignored inertia of coupling elements and the impacts between couplers.Thus,existing models underestimate the additional dynamic variations in in-train forces.Detailed multi-body dynamic models of two AAR(Association of American Railroads)coupler systems used in passenger and freight trains are developed,incorporating coupler inertia and various slacks.Due to the modeling and simulation com-plexities involved in a full train model,with such details of coupler system,actual longitudinal train dynamics is not studied.A system comprising only two coupling units,inter-connecting two consecutive vehicles,is modeled.Considered system has been fixed at one end and an excitation force is applied at the other end,to mimic a relative force transmission through combined coupler system.Simulation results obtained from this representative system show that,noticeable influence in in-train forces are expected due to the combined effect of inertia of couplers and intermittent impacts between couplers in the slack regime.Maximum amplitude of longitudinal reaction force,transferred from draft gear housing to vehicle body,is expected to be significantly higher than that predicted using existing models of coupler system.It is also observed that the couplers and knuckles are subjected to significant longitudinal and lateral contact forces,due to the intermittent impacts between couplers.Thus,accurate estimation of draft gear reaction force and impact forces between couplers are essential to design vehicle and coupler components,respectively.展开更多
Train dynamics and component fatigue assessments are important steps towards successful operations of long heavy haul trains.Longitudinal train dynamics(LTD)simulation is an effective and efficient approach in this re...Train dynamics and component fatigue assessments are important steps towards successful operations of long heavy haul trains.Longitudinal train dynamics(LTD)simulation is an effective and efficient approach in this regard.Draft gear friction has been known to have a strong stochastic feature.However,relevant train dynamics simulations have not been reported in open literature.This paper uses experimental data to extract the stochastic feature of draft gear friction.The stochastic feature is then introduced into LTD simulations.Coupler force and fatigue damage assessments were conducted by simulating a heavy haul train that has 244 vehicles and weighs nearly 30,000 tonnes.The results show that average in-train force variations due to stochastic friction were 55 and 40 kN for the traction and air brake cases respectively;maximum force variations were 207 and 98 kN for the traction and air brake cases respectively.Coupler fatigue calculations are even more sensitive to stochastic draft gear friction;the largest variations can be up to 700 times different due to the strong nonlinearity of fatigue calculation procedures.Stochastic friction is an unavoidable nature in friction draft gears.Simulations using stochastic draft gear friction can deliver results that are more robust and reliable.展开更多
文摘Rolling stock connection systems are key to running longer and heavier trains as they provide both the connections of vehicles and the damping,providing the longitudinal suspension of the train.This paper focuses on the evolution of both connection and stiffness damping systems.Focus is on freight rolling stock,but passenger draw gears are also examined.It was found that connection systems have evolved from the buff and chain system used in the pioneer railways of the 1800s to the modern auto-coupler connection systems that are in-service worldwide today.Refined versions of the buff and chain coupling are,however,still in use in the EU,UK,South America and India.A wide range of auto-coupler systems are currently utilised,but the AAR coupler(Janney coupler)remains the most popular.A further variation that persists is the SA3 coupler(improved Wilson coupler)which is an alternative auto-coupler design used mainly throughout the former Soviet Union.Restricting the review to auto-coupler systems allowed the paper to focus on draft gears which revealed polymer,polymer-friction,steel spring-friction,hydraulic draft gears and sliding sill cushioning systems.Along with the single compressive draft gear units balanced and floating plate configurations are also presented.Typical draft gear acceptance standards are presented along with modelling that was included to aid in presentation of the functional characteristics of draft gears.
文摘Inadequate management of large in-train forces transferred through coupler systems of a railway train leads to running and structural failures of vehicles.Understanding these phenomena and their mitigation requires accurate estimation of relative motions and in-train forces between vehicle bodies.Previous numerical studies have ignored inertia of coupling elements and the impacts between couplers.Thus,existing models underestimate the additional dynamic variations in in-train forces.Detailed multi-body dynamic models of two AAR(Association of American Railroads)coupler systems used in passenger and freight trains are developed,incorporating coupler inertia and various slacks.Due to the modeling and simulation com-plexities involved in a full train model,with such details of coupler system,actual longitudinal train dynamics is not studied.A system comprising only two coupling units,inter-connecting two consecutive vehicles,is modeled.Considered system has been fixed at one end and an excitation force is applied at the other end,to mimic a relative force transmission through combined coupler system.Simulation results obtained from this representative system show that,noticeable influence in in-train forces are expected due to the combined effect of inertia of couplers and intermittent impacts between couplers in the slack regime.Maximum amplitude of longitudinal reaction force,transferred from draft gear housing to vehicle body,is expected to be significantly higher than that predicted using existing models of coupler system.It is also observed that the couplers and knuckles are subjected to significant longitudinal and lateral contact forces,due to the intermittent impacts between couplers.Thus,accurate estimation of draft gear reaction force and impact forces between couplers are essential to design vehicle and coupler components,respectively.
文摘Train dynamics and component fatigue assessments are important steps towards successful operations of long heavy haul trains.Longitudinal train dynamics(LTD)simulation is an effective and efficient approach in this regard.Draft gear friction has been known to have a strong stochastic feature.However,relevant train dynamics simulations have not been reported in open literature.This paper uses experimental data to extract the stochastic feature of draft gear friction.The stochastic feature is then introduced into LTD simulations.Coupler force and fatigue damage assessments were conducted by simulating a heavy haul train that has 244 vehicles and weighs nearly 30,000 tonnes.The results show that average in-train force variations due to stochastic friction were 55 and 40 kN for the traction and air brake cases respectively;maximum force variations were 207 and 98 kN for the traction and air brake cases respectively.Coupler fatigue calculations are even more sensitive to stochastic draft gear friction;the largest variations can be up to 700 times different due to the strong nonlinearity of fatigue calculation procedures.Stochastic friction is an unavoidable nature in friction draft gears.Simulations using stochastic draft gear friction can deliver results that are more robust and reliable.
